We are studying the electrical activity in cat colon in vitro. Slow wave frequency and the coupling of slow waves are not affected by cholinergic agonists, adrenergic agonists, adrenergic alpha-antagonist, adrenergic beta-antagonist, tetrodotoxin and lidocaine. Migrating spike bursts during is prolonged by tetrodotoxin and lidocaine, but it is not affected by the above agonists and antagonists. This suggests that migrating spike burst represents periodic release of the muscle from the tonic influence of non-adrenergic inhibitory nerves in the intramural pleuses. Lowering the temperature from 37 degrees reduced the frequency of the slow wave of the colon. This suggests that frequency of slow wave is dependent upon the metabolic rate.